The present invention generally relates to a storage system and a takeover method of a logical unit in a storage system, and particularly relates to data migration technology where a plurality of storage apparatuses configuring a storage system dynamically take over a logical unit by operating in a cooperative distributed manner.
Pursuant to the increase in the data throughput of computer systems, the capacity of storage apparatuses storing data is also increasing. In addition, the growth in the amount of data in recent years is increasing drastically and, therefore, storage apparatuses must be enhanced or extended by necessity.
Japanese Patent Laid-Open Publication No. 2004-220450 (Patent Document 1) discloses technology for newly introducing a second storage apparatus to a computer system already comprising a first storage apparatus. Specifically, Patent Document 1 discloses technology of allocating a logical device of the newly introduced second storage apparatus to a logical device of the existing first storage apparatus so that a host computer recognizes the logical device of the existing first storage apparatus as the logical device of the newly introduced second storage apparatus. Patent Document 1 discloses technology for gradually migrating data in the first storage apparatus to the second storage apparatus.
Moreover, Japanese Patent Laid-Open Publication No. 2004-102374 (Patent Document 2) discloses data migration technology for migrating data in a storage area of a first storage subsystem to a second storage subsystem. Specifically, Patent Document 2 discloses technology of migrating, in accordance with the migration of data, the setting of a migration source storage subsystem to a migration destination storage subsystem and switching the access path of a computer to the migration destination storage subsystem using a remote management interface retained in both the migration source and migration destination storage subsystems.
Further, Japanese Patent Laid-Open Publication No. 2008-9707 (Patent Document 3) discloses data replication technology capable of mutually linking configuration information in two storage apparatuses. Specifically, Patent Document 3 discloses a storage system comprising a first storage apparatus for storing data from a host system, and a second storage apparatus for storing backup data of that data. In Patent Document 3, the first storage apparatus changes its configuration information based on a change request of confirmation information from the host system and sends the change request to the second storage apparatus, and the second storage apparatus changes its configuration information based on the change request.
Lastly, Japanese Patent Laid-Open Publication No. 2008-9767 discloses technology for dynamically securing a spare storage area from a storage area of an existing disk in order to ensure the fault tolerance of a storage apparatus.